Advances in polymerization and catalysis have resulted in the capability to produce many new polymers having improved physical and chemical properties useful in a wide variety of superior products and applications. With the development of new catalysts the choice of polymerization-type (solution, slurry, high pressure or gas phase) for producing a particular polymer has been greatly expanded. Also, advances in polymerization technology have provided more efficient, highly productive and economically enhanced processes. Especially illustrative of these advances is the development of technology utilizing bulky ligand metallocene-type catalyst systems.
More recently, developments have lead to the discovery of anionic, multidentate heteroatom ligands as discussed by the following articles: (1) Kempe et al., "Aminopyridinato Ligands--New Directions and Limitations", 80.sup.th Canadian Society for Chemistry Meeting, Windsor, Ontario, Canada, Jun. 1-4, 1997; (2) Kempe et al., Inorg. Chem. 1996 vol 35 6742; (3) Jordan et al. of polyolefin catalysts based on hydroxyquinolines (Bei, X.; Swenson, D. C.; Jordan, R. F., Organometallics 1997, 16, 3282); (4) Horton, et.al., "Cationic Alkylzirconium Complexes Based on a Tridentate Diamide Ligand: New Alkene Polymerization Catalysts", Organometallics, 1996, 15, 2672-2674 relates to tridentate zirconium complexes; (5) Baumann, et al., "Synthesis of Titanium and Zirconium Complexes that Contain the Tridentate Diamido Ligand [((t-Bu-d.sub.6)N--O--C.sub.6 H.sub.4).sub.2 O].sup.2- {[NON}.sup.2-) and the Living Polymerization of 1-Hexene by Activated [NON]ZrMe2", Journal of the American Chemical Society, Vol. 119, pp. 3830-3831; (6) Cloke et al., "Zirconium Complexes incorporating the New Tridentate Diamide Ligand [(Me.sub.3 Si)N{CH.sub.2 CH.sub.2 N(SiMe.sub.3)}.sub.2 ].sup.2- (L); the Crystal Structure of [Zr(BH.sub.4).sub.2 L] and [ZrCl{CH(SiMe.sub.3).sub.2 }L]", J. Chem. Soc. Dalton Trans, pp. 25-30, 1995; (7) Clark et al., "Titanium (IV) complexes incorporating the aminodiamide ligand [(SiMe.sub.3)N{CH.sub.2 CH.sub.2 N(SiMe.sub.3)}.sub.2 ].sup.2- L); the X-ray crystal structure of [TiMe.sub.2 (L)] and [TiCl{CH(SiMe.sub.3).sub.2 }(L)]", Journal of Organometallic Chemistry, Vol 50, pp. 333-340, 1995; (8) Scollard et al., "Living Polymerization of alpha-olefins by Chelating Diamide Complexes of Titanium", J. Am. Chem. Soc., Vol 118, No. 41, pp. 10008-10009, 1996; and (9) Guerin et al., "Conformationally Rigid Diamide Complexes: Synthesis and Structure of Titanium (IV) Alkyl Derivatives", Organometallics, Vol 15, No. 24, pp. 5085-5089, 1996.
Furthermore, U.S. Pat. No. 5,576,460 describes a preparation of arylamine ligands and U.S. Pat. No. 5,889,128 discloses a process for the living polymerization of olefins using initiators having a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. EP 893 454 A1 also describes preferably titanium transition metal amide compounds. In addition, U.S. Pat. No. 5,318,935 discusses amido transition metal compounds and catalyst systems especially for the producing isotactic polypropylene. Polymerization catalysts containing bidentate and tridentate ligands are further discussed in U.S. Pat. No. 5,506,184.
While all these compounds have been described in the art, there is still a need for an improved catalyst system.